Organ walls are composed of several layers: the mucosa (the surface layer), the submucosa, the muscularis (muscle layer), and the serosa (connective tissue layer). In gastrointestinal, colonic, and esophageal cancer, lesions or cancerous masses may form along the mucosa and often extend into the lumens of the organs. Conventionally, that condition is treated by cutting out a portion of the affected organ wall. This procedure, however, may cause discomfort to patients, and pose health risks.
Recently, physicians have adopted minimally invasive techniques called endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). EMR methods are typically used for removal of small cancerous or abnormal tissues (i.e., polyps), and ESD methods are typically used for en bloc removal of large cancerous or abnormal tissues (e.g., lesions).
ESD is generally performed with an endoscope, which is a long, narrow elongated member optionally equipped with a light, imaging equipment, and other instruments. During this procedure, the endoscope is passed down the throat or guided through the rectum to reach an abnormality such as a lesion or cancerous mass in an affected organ. The lesion is identified and marked with a tissue dissection device such as, for example, an electrosurgical needle knife that is extended through a working channel of the endoscope. Submucosal injections are made at the margins of the lesion to lift the mucosa, and the lesion is removed by dissection of the submucosal tissue under the lesion using the tissue dissection device.
It has been observed that in performing these ESD procedures, physicians sweep the tissue dissection device along similar paths to remove lesions from the organ wall. Specifically, physicians sweep the tissue dissection device across and under the lesion in a planar stroke. Occasionally, an upward stroke is included at the tail end of the planar stroke.
Based on these observations, it may be beneficial to provide a tissue dissection device that follows a prescribed path and has multiple degrees of freedom so as to provide uniform tissue excision in a safe and efficient manner.